1. On convergence of linear positive operators in the space of continuous functions;Korovkin;Doklady. Akad. Nauk SSSR,1953
2. On the order of approximation of functions by linear positive operators;Korovkin;Dokl. Akad. Nauk SSSR.,1957
3. On the exact inequality for linear positive operators of finite rank;Vidensky;Dokl. Akad. Nauk Tadzhik. SSR.,1981
4. Quantitative Korovkin type theorems on simultaneous approximation;Gonska;Math. Z.,1984
5. Ein Satz vom Korovkin-Type fur Ck Raume;Knoop;Math. Z.,1976